POS0215 PHENOTYPES AND DISEASE CHARACTERISTICS OF IgG4-RELATED DISEASE IN NORWAY
Authors: J. Vikse, Ø. Midtvedt, Ø. Molberg, B. T. Svanes Fevang, Ø. Palm, T. Garen, K. B. Norheim, G. Bakland, M. Wallenius, A. M. Hoffmann-Vold
Journal: Annals of the Rheumatic Diseases (2022)

Background Milestones in the field of IgG4-related disease (IgG4-RD) include the 2011 Comprehensive Diagnostic Criteria (CDC) (1), the 2019 ACR/EULAR classification criteria (2), and the recent identification of four distinct clinical phenotypes (3). Performance of the criteria and phenotypic disease expression in Scandinavian populations are largely unknown. Objectives Describe disease characteristics, phenotypes, and performance of the 2011 CDC and 2019 ACR/EULAR classification criteria in patients with IgG4-RD in Norway. Methods Consenting, adult patients with a clinical diagnosis of IgG4-RD, seen at the Department of Rheumatology, Oslo University Hospital were included. Two experts (JV, ØMi) assigned patients to phenotypes (”Pancreato-Hepato-Biliary”, “Retroperitoneum and Aorta”, “Head and Neck-Limited” or “Mikulicz and Systemic”) based on pattern of organ involvement. Fulfillment of the CDC and classification criteria were assessed. Disease activity and damage were scored with the IgG4-RD responder index (IgG4-RD RI). We used descriptive statistics. Results We identified 60 patients with IgG4-RD (Table 1). Clinical characteristics were as expected, with approximately equal number of patients in each phenotype group. Of all patients diagnosed by expert opinion, 42 (70%) fulfilled the ACR/EULAR classification criteria. Reasons for not fulfilling the criteria were (i) failure to meet the inclusion criterium (n = 3) due to “atypical” organ involvement: tonsils (n = 1), nasal cavity (n = 1); coronary artery (n = 1); (ii) presence of ≥ 1 exclusion criterium (n = 5): fever (n = 1), leukopenia (n = 1), thrombocytopenia (n = 1), positive anti-MPO-ANCA (n = 3), anti-SSA (n = 1) and/or anti-RNP (n = 1) antibody; and (iii) score &lt; 20 points (n = 10). In the latter group, 8 (80%) were not biopsied, and 1 (10%) had only performed fine needle biopsy. Among the patients not meeting the inclusion criterium or having ≥ 1 exclusion criteria, 1 (33%) and 4 (80%) scored ≥ 20 points, respectively. Of all patients, 56 (93%) fulfilled CDC, with 32 (53%), 10 (17%) and 14 (23%) patients characterized as “definite”, “probable” and “possible” IgG4-RD, respectively. Of the 18 patients not fulfilling the ACR/EULAR classification criteria, 15 (83%) fulfilled CDC (4 “definite”, 3 “probable”, 8 “possible”). Of the 4 patients not fulfilling CDC, 1 fulfilled the ACR/EULAR classification criteria. Table 1. All (60) Pancreato-Hepato-Biliary (14) Retroperitoneum and aorta (12) Head and Neck-Limited (17) Mikulicz and Systemic (17) Male, n (%) 44 (73) 11 (79) 9 (75) 10 (59) 14 (82) Caucasian, n (%) 52 (87) 14 (100) 11 (92) 13 (77) 14 (82) Age at diagnosis, years (SD) 60 (14) 66 (9) 64 (10) 50* (17) 61 (11) Time from onset to diagnosis, years (SD) 2 (3) 2 (3) 2 (4) 1 (1) 4 (5) Serum IgG4, g/L (SD) (n=51) 8 (9) 5 (5) 3 (2) 7 (5) 16* (13) Elevated baseline serum IgG4, n (%) (n=51) 44 (86) 9 (69) 10 (91) 11 (92) 14 (93) CRP, mg/dL (SD) 11 (26) 4 (7) 36* (52) 9 (17) 5 (4) ESR, mm/h (SD) 35 (32) 16 (11) 63* (36) 29 (29) 39 (30) Eosinophilia, n (%) (n=46) 17 (37) 2 (22) 0 6 (38) 9 (64) CDC definite, n (%) 32 (53) 10 (71) 3 (25) 8 (47) 11 (65) CDC probable, n (%) 10 (17) 3 (21) 1 (8) 5 (29) 1 (6) CDC possible, n (%) 14 (23) 0 6 (50) 4 (24) 4 (24) ACR/EULAR classification criteria, n (%) 42 (70) 13 (93) 5 (42) 8 (47) 16 (94) Number of involved organs (SD) Active, all 4 (2) 3 (2) 2 (2) 3 (1) 6* (2) Active, symptoms 2 (1) 2 (1) 1 (0) 2 (1) 3* (1) Active, urgent 1 (1) 1 (1) 1 (1) 0* (0) 1 (1) Damage 2 (1) 2* (1) 1 (1) 1 (1) 2* (2) IgG4-RD RI (SD) 10 (5) 9 (4) 7 (4) 7 (3) 15* (4) *p &lt; 0,05 by one-way ANOVA Conclusion Despite expected clinical characteristics, phenotype distribution and fulfilment of CDC in our cohort, the performance of the ACR/EULAR classification criteria was lower than expected, especially in the “Retroperitoneum and Aorta” and “Head and Neck-Limited” phenotypes. This may have important implications for the comparability across studies and inclusion in future clinical trials. References [1]Umehara et al. Mod Rheumatol. 2012;22(1):21-30. [2]Wallace et al. Ann Rheum Dis. 2020;79(1):77-87. [3]Wallace et al. Ann Rheum Dis. 2019;78(3):406-412 Disclosure of Interests Jens Vikse Speakers bureau: Novartis, Consultant of: Novartis, Jupiter Life Science Consulting, Øyvind Midtvedt: None declared, Øyvind Molberg: None declared, Bjørg Tilde Svanes Fevang: None declared, Øyvind Palm: None declared, Torhild Garen: None declared, Katrine Brække Norheim: None declared, Gunnstein Bakland: None declared, Marianne Wallenius: None declared, Anna-Maria Hoffmann-Vold Speakers bureau: Actelion, Boehringer Ingelheim, Jansen, Lilly, Medscape, Merck Sharp &amp; Dohme, Roche, Consultant of: Actelion, ARXX, Bayer, Boehringer Ingelheim, Jansen, Lilly, Medscape, Merck Sharp &amp; Dohme, Roche, Grant/research support from: Boehringer Ingelheim